Many electronic devices include one or more rechargeable batteries that require external power to recharge from time to time. Often, these devices may be charged using a similar power cord or connector, for example a universal serial bus (“USB”) connector. However, despite having common connection types, devices often require separate power supplies with different power outputs. These multiple power supplies can be burdensome to use, store, and transport from place to place. As a result, the benefits of device portability may be substantially limited.
Furthermore, charging cords may be unsafe to use in certain circumstances. For example, a driver of a vehicle may become distracted attempting to plug an electronic device into a vehicle charger. In another example, a charging cord may present a tripping hazard if left unattended.
To account for these and other shortcomings of portable electronic devices, some devices include an inductive charging system. The user may simply place the device on an inductive charging surface of a charging device in order to charge the battery. The charging device can detect the presence of the electronic device on the inductive charging surface by pinging or transmitting power to the electronic device for a given time period and waiting to receive a response (e.g., a communication signal) from the electronic device. If the electronic device is not on the inductive charging surface, a response is not received from the electronic device and the charging device stops pinging. The charging device may then ping periodically until a communication signal is received from the electronic device.
Periodic pinging, however, consumes power and can reduce the charge on the battery. For example, if the electronic device is not present for twelve hours, periodic pinging can consume power needlessly. The time interval between pings can be increased to save power, but this slows the response time of the charging device. For example, the charging device can ping every minute, but up to a minute can pass before the charging device responds by transmitting power to the electronic device.